Overview

Zinc is a mineral considered an “essential trace element” because small amounts of it are required for human health. Indeed, zinc is involved in such essential processes as immune function, enzyme activity, and DNA synthesis.

Zinc is used to treat a large variety of medical concerns, including cold and ear infections and skin conditions such as acne.

In addition, zinc has been suggested to slow the progression of age-related macular degeneration (AMD) – the leading cause of vision loss in people aged 50 and up.

Although zinc deficiency is relatively rare in developed countries, it is estimated to affect as many as 2 billion people in the developing world.1

How Zinc May Help with Eye Health

Retinal function

Although zinc is found throughout many different tissues, it is is highly concentrated in the the retina – the region at the back of the eye that receives light and sends electric signals to the brain. The retina includes an area called the macula, which is the region affected by age-related macular degeneration (AMD) – the leading cause of blindness in developed countries.2

Researchers believe that zinc plays a key role in the development of AMD because:

Vitamin A function

Zinc is also required for the proper function and utilization of vitamin A, which is involved in several aspects of vision. Most notably, zinc is needed to transport vitamin A in the blood, and to convert it to retinal, which is required to synthesize rhodopsin, a protein that helps the eye adapt to darkness.

Zinc’s Uses & Benefits for Vision

Zinc is most commonly used in a multi-ingredient formulas that support eye health. The findings of the highly influential Age-Related Eye Disease Study (AREDS) suggest that a mix of zinc and antioxidants significantly reduce the risk of the progression of age-related macular degeneration (AMD). As a result, most people tend to use this specific formula rather than single-ingredient zinc supplements.

Research

Human Research

The majority of studies suggest that zinc supplementation alone and especially in combination with antioxidants is associated with reduced risk of the development and progression of age-related macular degeneration (AMD). Meanwhile, the one negative study can be explained by its relatively short duration (2 years).

This large double-blind, randomized clinical trial sponsored by the U.S. National Institutes of Health examined whether high doses of vitamin C, vitamin E, beta-carotene and zinc could slow the progression of AMD. A total of 3640 people were given one of four treatments: antioxidants (vitamin C, 500 mg; vitamin E, 400 IU; and beta carotene, 15 mg); zinc (80 mg zinc oxide 2 mg copper oxide); antioxidants plus zinc; or placebo. After an average of 6.3 years, all three treatments were found to reduce the odds of developing advanced AMD, with the combination treatment having the best results.

The researchers concluded that “Those with extensive intermediate size drusen, at least 1 large druse, noncentral geographic atrophy in 1 or both eyes, or advanced AMD or vision loss due to AMD in 1 eye, and without contraindications such as smoking, should consider taking a supplement of antioxidants plus zinc“3

In this randomized clinical trial 80 people with dry age-related macular degeneration (AMD) were given zinc-monocysteine (ZMC 50 mg) or placebo daily for 6 months. At the end of the study, people in the ZMC group had improved sharpness of vision and contrast sensitivity. In addition, they also experienced an improvement in macular light flash recovery time.

The researchers concluded that “ZMC 25 mg twice daily was well tolerated and was associated with improved macular function in comparison to a placebo in persons with dry AMD“4

This double-blind, randomized study examined the effects of zinc on vision in people with macular degeneration. One hundred fifty-one people (aged 42-89) with were given zinc sulfate (200 mg) or placebo daily for two years. The study found that people in the zinc group had significantly less visual loss than placebo.

The researchers concluded that “Our data indicate that in our study group of persons with macular degeneration, the use of oral zinc sulfate was associated with a retardation of visual loss“5

This study explored the link between intake of beta carotene, vitamins C and E, and zinc and progression of AMD in 5836 people over 14 years. The study found that intake of both vitamin E and zinc was inversely associated with developing AMD, and that above-median intake of all 4 nutrients — beta carotene, vitamin C, vitamin E, and zinc — was associated with a 35% reduced risk of AMD.

The researchers concluded that ” high dietary intake of beta carotene, vitamins C and E, and zinc was associated with a substantially reduced risk of AMD in elderly persons“6

This double-blind, randomized trial tested the hypothesis that zinc and vitamin A may play a role in night blindness. A total of 202 pregnant women with night blindness received one of the following treatments daily for 3 weeks: beta-carotene + zinc, beta-carotene alone, vitamin A + zinc, vitamin A alone, zinc alone, and placebo. The study found that women in the vitamin A + zinc group were 4 times as likely to have their night vision restored as the placebo group.

The researchers concluded that “zinc potentiated the effect of vitamin A in restoring night vision among night-blind pregnant women with low initial serum zinc concentrations“7

This double-blind, randomized study tested whether zinc supplementation can help individuals with age-related macular degeneration (AMD) in one eye. One hundred twelve patients were given zinc sulfate (200 mg) or placebo daily for 2 years. Although blood zinc levels increased in the treatment group, there was no significant effect on the progression of AMD.

The researchers concluded that “Oral zinc substitution has no short-term effect on the course of age-related macular degeneration in patients who have an exudative form of the disease in one eye“8

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Dosage for Vision Performance

Research suggests that zinc doses of 50-200 mg are effective for supporting eye health

Most single-ingredient zinc supplements supply doses of 30-50 mg

Multi-ingredient eye health formulations typically provide 40 mg

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Supplements in Review Recommendation

Zinc as part of AREDS eye formula, twice daily.

Research suggests that zinc supplementation can help people with AMD. Given that AMD is the leading cause of vision loss in the developed world, supplementing zinc is a good idea for adults aged 50 and over.

This zinc dosage is supported by two large-scale, multi-year clinical trials. The AREDS 1 & 2 studies recommend taking 80 mg of zinc with specific antioxidants to slow the progression of AMD.